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 * The Universal Permissive License (UPL), Version 1.0
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 * data (collectively the "Software"), free of charge and under any and all
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 * (a) the Software, and
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 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
 * one is included with the Software each a "Larger Work" to which the Software
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package com.oracle.truffle.espresso.hotswap;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

final class HotSwapHandler {

    private static HotSwapHandler theHandler;

    private final Set<HotSwapPlugin> plugins = Collections.synchronizedSet(new HashSet<>());
    private final Map<Class<?>, Set<HotSwapAction>> hotSwapActions = new HashMap<>();
    private final List<HotSwapAction> postHotSwapActions = Collections.synchronizedList(new ArrayList<>());
    private final Map<Class<?>, Boolean> staticInitializerHotSwap = new HashMap<>();
    private final Map<Class<?>, List<HotSwapAction>> staticReInitCallBacks = new HashMap<>();
    private final ServiceWatcher serviceWatcher = new ServiceWatcher();

    private HotSwapHandler() {
    }

    static HotSwapHandler create() {
        theHandler = new HotSwapHandler();
        // register handler to Espresso if present
        return registerHandler(theHandler) ? theHandler : null;
    }

    // substituted by Espresso
    private static boolean registerHandler(@SuppressWarnings("unused") Object handler) {
        return false;
    }

    void addPlugin(HotSwapPlugin plugin) {
        plugins.add(plugin);
    }

    public void registerHotSwapAction(Class<?> klass, HotSwapAction action) {
        hotSwapActions.putIfAbsent(klass, new HashSet<>());
        hotSwapActions.get(klass).add(action);
    }

    public void registerPostHotSwapAction(HotSwapAction action) {
        postHotSwapActions.add(action);
    }

    public void registerStaticClassInitHotSwap(Class<?> klass, boolean onChange, HotSwapAction callback) {
        if (!staticInitializerHotSwap.containsKey(klass)) {
            staticInitializerHotSwap.put(klass, onChange);
        } else if (!onChange) {
            staticInitializerHotSwap.put(klass, false);
        }
        if (callback != null) {
            List<HotSwapAction> reInitCallbacks = staticReInitCallBacks.get(klass);
            if (reInitCallbacks == null) {
                reInitCallbacks = new ArrayList<>(1);
                staticReInitCallBacks.put(klass, reInitCallbacks);
            }
            reInitCallbacks.add(callback);
        }
    }

    public void registerMetaInfServicesListener(Class<?> service, ClassLoader loader, HotSwapAction callback) {
        serviceWatcher.addServiceWatcher(service, loader, callback);
    }

    @SuppressWarnings("unused")
    public void postHotSwap(Class<?>[] changedClasses) {
        // fire all registered HotSwap actions
        for (Class<?> klass : changedClasses) {
            Set<HotSwapAction> actions = hotSwapActions.getOrDefault(klass, Collections.emptySet());
            actions.forEach(HotSwapAction::fire);
        }
        // fire a generic HotSwap plugin listener
        for (HotSwapPlugin plugin : plugins) {
            plugin.postHotSwap(changedClasses);
        }
        // fire all registered post HotSwap actions
        postHotSwapActions.forEach(HotSwapAction::fire);
    }

    @SuppressWarnings("unused")
    public boolean shouldRerunClassInitializer(Class<?> klass, boolean changed) {
        if (staticInitializerHotSwap.containsKey(klass)) {
            boolean onlyOnChange = staticInitializerHotSwap.get(klass);
            boolean rerun = !onlyOnChange || changed;
            if (rerun) {
                staticReInitCallBacks.getOrDefault(klass, Collections.emptyList()).forEach(HotSwapAction::fire);
            }
            return rerun;
        } else {
            // check class hierarchy
            for (Map.Entry<Class<?>, Boolean> entry : staticInitializerHotSwap.entrySet()) {
                Class<?> key = entry.getKey();
                if (key.isAssignableFrom(klass)) {
                    boolean rerun = !entry.getValue() || changed;
                    if (rerun) {
                        staticReInitCallBacks.getOrDefault(key, Collections.emptyList()).forEach(HotSwapAction::fire);
                    }
                    return rerun;
                }
            }
        }
        return false;
    }
}
